Digital cameras and optical imaging devices employ image sensors. Image sensors convert optical images to digital data that may be represented as a digital image. Image sensors include an array of pixels, which are unit devices for the conversion of the optical image into digital data. The pixels often manifest themselves as charge-coupled devices (CCDs) or complementary metal oxide semiconductor (CMOS) sensors. While CMOS image sensors (CIS) devices have been more recently developed compared to CCDs, CIS devices provide an advantage of lower power consumption, smaller size, and faster data processing than CCDs as well as direct digital output that is not available in CCDs. Also, CIS devices have lower manufacturing cost compared with CCDs since many standard semiconductor manufacturing processes may be employed to manufacture CIS devices. For these reasons, commercial employment of CIS devices has been steadily increasing in recent years.